﻿CRETACEOUS BRACHIOPODA. 



53 



67. Waldheimia hippopus, Roemer, sp. (?), Var. Tilbyensis. Sup., PI. VI, figs. 10, 11. 



Terebrattjla hippopus, Roemer. Norddeutsche Kreide, p. 1 14, pi. xvi, fig. 28 ; Hils- 



conglomerat Berklingen, 1841. 

 — — Judd. Quarterly Journal Geol. Soc, vol. xxiii, p. 245, 1868. 



Spec. Char. Shell circular or elongated oval, widest about the middle, more or less 

 ventricose, and thickened laterally. Dorsal valve convex at the umbo and along the 

 lateral portions of the valve, gradually concave or longitudinally furrowed along the 

 middle ; ventral valve much deeper and more convex than the opposite one, longi- 

 tudinally keeled and flattened at the sides. Beak much incurved and truncated by a 

 minute foramen, slightly separated from the hinge-line by a deltidiurn in two pieces ; 

 beak-ridges acutely defined, leaving between them and the hinge-line a narrow concave 

 space. Surface smooth, marked only with concentric lines of growth. Loop 

 extending to near the front before becoming deflected. 

 Length 6, width 5^, depth 4 lines. 



Obs. In 1841 Roemer figured and described under the name of hippopus a small 

 and well-characterised shell occurring plentifully in the Upper Salzgitter Hills in 

 Hanover. The larger number of specimens of Roemer's species that have fallen under 

 my observation were much thickened, elongated oval, and not much exceeding seven 

 lines in length by five in breadth, and with the sinus very much restricted to the 

 longitudinal central portion of the valve. Among the specimens, however, there did 

 occur a few in which the length and width were nearly equal and the sinus much more 

 broadly concave or dilated. 



As is usually the case when a description and illustration is taken from a simgle 

 specimen, it is not easy to appreciate the general character pertaining to the species, 

 or rather the modifications in shape it is capable of assuming ; hence if a number of large 

 and totally different forms which have been referred by different Palaeontologists to the small 

 Salzgitter shell. As justly observed by M. de Loriol in a note he has added to page 

 105 of Pictet's description of the Cretaceous Brachiopoda from the neighbourhood of 

 Sainte-Croix, " the German authors have on several occasions pointed out this error 

 (see Strombeck, 1861 ; ' Ueber den Gault in N. W. Deutschland, Zeitschrift der Deutschen 

 Geol. Gesell,' 1861, p. 45; Herm. Credner, ' Brachiopoden der Hilsbildung, Zeitsch.' 

 &c, 1864; also Schloenbach, ' Leonh. und Bronn's Neues Jahrbuch,' 1866, p. 575. 

 ' Kritische Studien iiber Kreide-Brachiopoden,' 1866, p. 33, and 'Brachiopoden der Nord- 

 deutschen Cenoman-Bildungen,' p. 94). They even see two species in those figured by 

 D'Orbigny under the false name of T. hippopus: the one represented by figures 12, 13, 

 14, of PI. 508 of the Paleontologie Francaise ; the other corresponding to figures 15 — 18 



